You might want to disable debug mode (aka. show_exceptions setting) unless you want people to have access to sensitive information like the one contained in the "firebase.rb" file or "/root/nginx-unicorn-sinatra/app.rb". Sending an invalid User-Agent as part of the HTTP requests (like one with Unicode characters) makes the web application fail and respond with a dump of the global _SERVER variable with additional information provided by the Sinatra framework:
curl -H "User-Agent: Foo — Bar" "http://serverlessly.io/"